This is version 6 of task, css_task and css iters support.
--- Changelog ---
v5 -> v6:
Patch #3:
* In bpf_iter_task_next, return pos rather than goto out. (Andrii)
Patch #2, #3, #4:
* Add the missing __diag_ignore_all to avoid kernel build warning
Patch #5, #6, #7:
* Add Andrii's ack
Patch #8:
* In BPF prog iter_css_task_for_each, return -EPERM rather than 0, and
ensure stack_mprotect() in iters.c not success. If not, it would cause
the subsequent 'test_lsm' fail, since the 'is_stack' check in
test_int_hook(lsm.c) would not be guaranteed.
(https://github.com/kernel-patches/bpf/actions/runs/6489662214/job/17624665086?pr=5790)
v4 -> v5:https://lore.kernel.org/lkml/[email protected]/
Patch 3~4:
* Relax the BUILD_BUG_ON check in bpf_iter_task_new and bpf_iter_css_new to avoid
netdev/build_32bit CI error.
(https://netdev.bots.linux.dev/static/nipa/790929/13412333/build_32bit/stderr)
Patch 8:
* Initialize skel pointer to fix the LLVM-16 build CI error
(https://github.com/kernel-patches/bpf/actions/runs/6462875618/job/17545170863)
v3 -> v4:https://lore.kernel.org/all/[email protected]/
* Address all the comments from Andrii in patch-3 ~ patch-6
* Collect Tejun's ack
* Add a extra patch to rename bpf_iter_task.c to bpf_iter_tasks.c
* Seperate three BPF program files for selftests (iters_task.c iters_css_task.c iters_css.c)
v2 -> v3:https://lore.kernel.org/lkml/[email protected]/
Patch 1 (cgroup: Prepare for using css_task_iter_*() in BPF)
* Add tj's ack and Alexei's suggest-by.
Patch 2 (bpf: Introduce css_task open-coded iterator kfuncs)
* Use bpf_mem_alloc/bpf_mem_free rather than kzalloc()
* Add KF_TRUSTED_ARGS for bpf_iter_css_task_new (Alexei)
* Move bpf_iter_css_task's definition from uapi/linux/bpf.h to
kernel/bpf/task_iter.c and we can use it from vmlinux.h
* Move bpf_iter_css_task_XXX's declaration from bpf_helpers.h to
bpf_experimental.h
Patch 3 (Introduce task open coded iterator kfuncs)
* Change th API design keep consistent with SEC("iter/task"), support
iterating all threads(BPF_TASK_ITERATE_ALL) and threads of a
specific task (BPF_TASK_ITERATE_THREAD).（Andrii)
* Move bpf_iter_task's definition from uapi/linux/bpf.h to
kernel/bpf/task_iter.c and we can use it from vmlinux.h
* Move bpf_iter_task_XXX's declaration from bpf_helpers.h to
bpf_experimental.h
Patch 4 (Introduce css open-coded iterator kfuncs)
* Change th API design keep consistent with cgroup_iters, reuse
BPF_CGROUP_ITER_DESCENDANTS_PRE/BPF_CGROUP_ITER_DESCENDANTS_POST
/BPF_CGROUP_ITER_ANCESTORS_UP(Andrii)
* Add KF_TRUSTED_ARGS for bpf_iter_css_new
* Move bpf_iter_css's definition from uapi/linux/bpf.h to
kernel/bpf/task_iter.c and we can use it from vmlinux.h
* Move bpf_iter_css_XXX's declaration from bpf_helpers.h to
bpf_experimental.h
Patch 5 (teach the verifier to enforce css_iter and task_iter in RCU CS)
* Add KF flag KF_RCU_PROTECTED to maintain kfuncs which need RCU CS.(Andrii)
* Consider STACK_ITER when using bpf_for_each_spilled_reg.
Patch 6 (Let bpf_iter_task_new accept null task ptr)
* Add this extra patch to let bpf_iter_task_new accept a 'nullable'
* task pointer(Andrii)
Patch 7 (selftests/bpf: Add tests for open-coded task and css iter)
* Add failure testcase(Alexei)
Changes from v1(https://lore.kernel.org/lkml/[email protected]/):
- Add a pre-patch to make some preparations before supporting css_task
iters.(Alexei)
- Add an allowlist for css_task iters(Alexei)
- Let bpf progs do explicit bpf_rcu_read_lock() when using process
iters and css_descendant iters.(Alexei)
---------------------
In some BPF usage scenarios, it will be useful to iterate the process and
css directly in the BPF program. One of the expected scenarios is
customizable OOM victim selection via BPF[1].
Inspired by Dave's task_vma iter[2], this patchset adds three types of
open-coded iterator kfuncs:
1. bpf_task_iters. It can be used to
1) iterate all process in the system, like for_each_forcess() in kernel.
2) iterate all threads in the system.
3) iterate all threads of a specific task
2. bpf_css_iters. It works like css_task_iter_{start, next, end} and would
be used to iterating tasks/threads under a css.
3. css_iters. It works like css_next_descendant_{pre, post} to iterating all
descendant css.
BPF programs can use these kfuncs directly or through bpf_for_each macro.
link[1]: https://lore.kernel.org/lkml/[email protected]/
link[2]: https://lore.kernel.org/all/[email protected]/
Chuyi Zhou (8):
cgroup: Prepare for using css_task_iter_*() in BPF
bpf: Introduce css_task open-coded iterator kfuncs
bpf: Introduce task open coded iterator kfuncs
bpf: Introduce css open-coded iterator kfuncs
bpf: teach the verifier to enforce css_iter and task_iter in RCU CS
bpf: Let bpf_iter_task_new accept null task ptr
selftests/bpf: rename bpf_iter_task.c to bpf_iter_tasks.c
selftests/bpf: Add tests for open-coded task and css iter
include/linux/bpf_verifier.h | 19 ++-
include/linux/btf.h | 1 +
include/linux/cgroup.h | 12 +-
kernel/bpf/cgroup_iter.c | 65 ++++++++
kernel/bpf/helpers.c | 9 ++
kernel/bpf/task_iter.c | 151 ++++++++++++++++++
kernel/bpf/verifier.c | 86 ++++++++--
kernel/cgroup/cgroup.c | 18 ++-
.../testing/selftests/bpf/bpf_experimental.h | 19 +++
.../selftests/bpf/prog_tests/bpf_iter.c | 18 +--
.../testing/selftests/bpf/prog_tests/iters.c | 150 +++++++++++++++++
.../{bpf_iter_task.c => bpf_iter_tasks.c} | 0
tools/testing/selftests/bpf/progs/iters_css.c | 72 +++++++++
.../selftests/bpf/progs/iters_css_task.c | 47 ++++++
.../testing/selftests/bpf/progs/iters_task.c | 41 +++++
.../selftests/bpf/progs/iters_task_failure.c | 105 ++++++++++++
16 files changed, 771 insertions(+), 42 deletions(-)
rename tools/testing/selftests/bpf/progs/{bpf_iter_task.c => bpf_iter_tasks.c} (100%)
create mode 100644 tools/testing/selftests/bpf/progs/iters_css.c
create mode 100644 tools/testing/selftests/bpf/progs/iters_css_task.c
create mode 100644 tools/testing/selftests/bpf/progs/iters_task.c
create mode 100644 tools/testing/selftests/bpf/progs/iters_task_failure.c
--
2.20.1
This patch adds kfuncs bpf_iter_task_{new,next,destroy} which allow
creation and manipulation of struct bpf_iter_task in open-coded iterator
style. BPF programs can use these kfuncs or through bpf_for_each macro to
iterate all processes in the system.
The API design keep consistent with SEC("iter/task"). bpf_iter_task_new()
accepts a specific task and iterating type which allows:
1. iterating all process in the system (BPF_TASK_ITER_ALL_PROCS)
2. iterating all threads in the system (BPF_TASK_ITER_ALL_THREADS)
3. iterating all threads of a specific task (BPF_TASK_ITER_PROC_THREADS)
Signed-off-by: Chuyi Zhou <[email protected]>
---
kernel/bpf/helpers.c | 3 +
kernel/bpf/task_iter.c | 90 +++++++++++++++++++
.../testing/selftests/bpf/bpf_experimental.h | 5 ++
3 files changed, 98 insertions(+)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index c01441db9fd5..c25941531265 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2563,6 +2563,9 @@ BTF_ID_FLAGS(func, bpf_iter_task_vma_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_iter_css_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_iter_css_task_next, KF_ITER_NEXT | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_iter_css_task_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_iter_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_iter_task_next, KF_ITER_NEXT | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_iter_task_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_dynptr_adjust)
BTF_ID_FLAGS(func, bpf_dynptr_is_null)
BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index e4126698cecf..faa1712c1df5 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -952,6 +952,96 @@ __bpf_kfunc void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it)
__diag_pop();
+struct bpf_iter_task {
+ __u64 __opaque[3];
+} __attribute__((aligned(8)));
+
+struct bpf_iter_task_kern {
+ struct task_struct *task;
+ struct task_struct *pos;
+ unsigned int flags;
+} __attribute__((aligned(8)));
+
+enum {
+ /* all process in the system */
+ BPF_TASK_ITER_ALL_PROCS,
+ /* all threads in the system */
+ BPF_TASK_ITER_ALL_THREADS,
+ /* all threads of a specific process */
+ BPF_TASK_ITER_PROC_THREADS
+};
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+ "Global functions as their definitions will be in vmlinux BTF");
+
+__bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it,
+ struct task_struct *task, unsigned int flags)
+{
+ struct bpf_iter_task_kern *kit = (void *)it;
+
+ BUILD_BUG_ON(sizeof(struct bpf_iter_task_kern) > sizeof(struct bpf_iter_task));
+ BUILD_BUG_ON(__alignof__(struct bpf_iter_task_kern) !=
+ __alignof__(struct bpf_iter_task));
+
+ kit->task = kit->pos = NULL;
+ switch (flags) {
+ case BPF_TASK_ITER_ALL_THREADS:
+ case BPF_TASK_ITER_ALL_PROCS:
+ case BPF_TASK_ITER_PROC_THREADS:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (flags == BPF_TASK_ITER_PROC_THREADS)
+ kit->task = task;
+ else
+ kit->task = &init_task;
+ kit->pos = kit->task;
+ kit->flags = flags;
+ return 0;
+}
+
+__bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it)
+{
+ struct bpf_iter_task_kern *kit = (void *)it;
+ struct task_struct *pos;
+ unsigned int flags;
+
+ flags = kit->flags;
+ pos = kit->pos;
+
+ if (!pos)
+ return pos;
+
+ if (flags == BPF_TASK_ITER_ALL_PROCS)
+ goto get_next_task;
+
+ kit->pos = next_thread(kit->pos);
+ if (kit->pos == kit->task) {
+ if (flags == BPF_TASK_ITER_PROC_THREADS) {
+ kit->pos = NULL;
+ return pos;
+ }
+ } else
+ return pos;
+
+get_next_task:
+ kit->pos = next_task(kit->pos);
+ kit->task = kit->pos;
+ if (kit->pos == &init_task)
+ kit->pos = NULL;
+
+ return pos;
+}
+
+__bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it)
+{
+}
+
+__diag_pop();
+
DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
static void do_mmap_read_unlock(struct irq_work *entry)
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 6792ed2b45d7..2f6c747aa874 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -465,5 +465,10 @@ extern int bpf_iter_css_task_new(struct bpf_iter_css_task *it,
extern struct task_struct *bpf_iter_css_task_next(struct bpf_iter_css_task *it) __weak __ksym;
extern void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it) __weak __ksym;
+struct bpf_iter_task;
+extern int bpf_iter_task_new(struct bpf_iter_task *it,
+ struct task_struct *task, unsigned int flags) __weak __ksym;
+extern struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) __weak __ksym;
+extern void bpf_iter_task_destroy(struct bpf_iter_task *it) __weak __ksym;
#endif
--
2.20.1